1. The Cell
All living things are made up of small individual units called…
cells!!!
Let’s look at the history of the cell…

2. Cell History
The first person to observe cells was British scientist named Robert Hooke.
Hooke used a magnifying glass to look at cork, where he observed boxlike openings he called cells.
NOTE: Hooke never saw living cells, though he coined the term.

3. Cell History again…
In 1683 Anton van Leeuwenhoek (LAY-ven-huke) saw the first living cells.
Leeuwenhoek used the first microscope to view his specimens.

4. More Cell History?
In 1824 Henry Dutrochet of France proposed that all living things are made of cells.
Matt Schleiden states all plants are made of cells, while Theodor Schwann says all animals are made of cells.

5. Please!!! No more cell history…
1855 Rudolf Virchow states that all cells come from preexisting cells.

6. Cells come from cells?
Prior to Virchow, most people (scientists included) were under the false assumption that life could come about through spontaneous generation.
Spontaneous generation of life is called parthenogenesis!!!

7. Virchow’s hypothesis…
How did Virchow disprove parthenogenesis?
He probably saw this .mov clip…

8. Putting it together…
With all of this info about the cell, gathered over the course of roughly 300 years, scientists were able to formulate the cell theory!!!

9. Cell Theory: All organisms are made of one or more cell.
2) All cells carry on life activities.
New cells arise from preexisting cells through the process of cell division.

10. Teeny Tiny Cells? Why are cells so small?
Must be able to interact with their surrounding environment.
Nutrients must be transported into the cell.
Waste must be transported out.

11. Limit to cell size: Surface area-to-volume-ratio limits cell size
As cell size increases, the S.A. increases as a power of 2, whereas the volume increases as a power of 3.
The larger the cell, the lower the S.A.-V ratio.